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Raspberry Pi Overclocking Guide – Cheap, Fun, and Overclockable (with HWBOT Prime) (Page 2)

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nice guide M

I've been testing Arch Linux with Java 8 preview, no real gains there.

Closing some processes might help you a little bit, but 'ps aux' (linux task manager) doesn't show any process that is taking a lot of cpu time

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From what I see, the Vin doesn't affect the final Varm. I see my Vin dropping to 4.7V now, but the Varm still measures 1.4V. Seems like the Varm voltage will be fixed regardless of what the Vin is.

 

I also read on the official RPi forums that the limit of 1.4V is hardware related, not firmware.

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I think I found the external bits of the internal VRM. If I did, it's EPower time.

First thing though is getting an install on there that will actually overclock.

I'll post a few pictures in a bit here, need to take 'em and do some classy MSPaint work.

 

 

EDIT:

Here we go:

PiOC-top.jpg

PiOC-bottom.jpg

 

Your mileage may vary, void where prohibited by law, not responsible for bad descisions, etc.

I have a hell of a time making SD cards, so it may be a bit till I can test this.

Putting some appropriate voltage caps across those two MLC jobs may well help, there's about 10mV of switching ripple on the VARM line, plus any transient ripple at higher loads. This is all at idle (no display attached, no Ethernet attached, booting to a command prompt I'd assume.), load ripple will be higher. Of course, more caps may blow things to hell, who knows.

 

 

 

 

If you do and it is Varm and you make WRs, if you could credit me that'd be great :D

Edited by Bobnova

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you can find some schematics of the board online. I was just looking at them to notice that one possibility is indeed to do the same thing as mentioned above:

 

Remove L5 and connect some external source to the point where you read the core voltage.

Maybe L5 can stay in place and you just connect some external source to the voltage readout point, but it would not be the proper way of doing things. Don't know how things have changed or got better the last few years in overclocking :)

 

The only thing that bothers me is the voltage feedback which could be monitoring the output voltage for low and high overvoltage. I need my Raspberry for programming stuff so I won't be testing it anyway :)

Edited by geoffrey

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Grabbed some time to redo the Raspbian(or whatever it is) install in the hopes that OCing will work. If it does it's external VRM time.

I'm torn between something simple like a heavily heatsinked adjustable linear regulator (it's only 3.5w stock max draw for the whole board, that's not bad linear reg wise) or going whole hog and EPowering it. The linear reg would be nice from the standpoint of starting up along with the board for proper(ish) timing, but the EPower is just so much more me.

 

It all depends on whether the damn thing will OC. If it won't OC adding voltage isn't exactly useful.

 

Pi was free, if it dies I'll be annoyed, but I don't use it much. Maybe I can get a sample from someone to replace it if I give 'em some press.

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You're correct on the read points. This is what I meaured (tested with changing the voltages)

 

readout.jpg

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Hey Pieter, in

$ sudo apt-get remove openjre-7-jdk
it should say openjdk-7-jre (or 6)

 

OR sudo apt-get purge openjdk*

 

Btw, I see there is a new build b102, here's the donwload link for ARM http://www.java.net/download/jdk8/archive/b102/binaries/jdk-8-ea-b102-linux-arm-vfp-hflt-07_aug_2013.tar.gz

 

Changelog: http://download.java.net/jdk8/changes/jdk8-b102.html?q=download/jdk8/changes/jdk8-b102.html

Edited by GENiEBEN

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I tried the hardware modification with a linear voltage regulator but with no help. It does work, but I could not get higher clocks on the pi, in contrary my SD cards got corrupted as soon as I tried +1200MHz... L5 is back where it belongs now, I'm done with overclocking the pi :)

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no pics, didn't draw any schematics but the mod is explained on the previous page I think: remove L5 on the downside of the board, take a variable linear voltage regulator, feed it from another USB post, hook up both (Vregulator and R-pi) GND lines and attach the regulators Vout to the Raspberry-pi Vcore readout point.

Linear is not the best choice though, even with this low current dev-board I notice a lot of voltage swings between idle and load.

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The swings might have been the cause of the SD-Card corruption. No voltage scaling doesn't make sense. Maybe you were just limited by the instable voltages?

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This got me about 40 MHz more on the core @ 1.4v and also about 40-50ish on the memory. The actual temp was around -24 according to temp gun and raspbian:P

It's just a stock prometia btw. I think I need to do some modding on the raspberry.

 

Let's say I use E-Power, I just remove L5 and connect E-Power to the V readout and a ground?

 

SF72lMvl.jpg

Edited by rsnubje

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It's exactly like they said in this topic. Remove L5 and put power from Epower on Varm readout and I used the other side of the resistor as ground.

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